Sensitivity of larval Dendropsophus haddadi (Bastos and Pombal 1996), an anuran species from the Brazilian Atlantic Forest, to acute exposure to nitrate.

Abstract

Nitrogenous pollution has been reported to be a major threat to biodiversity and, therefore, it may be related to the decline of amphibians, the most threatened group of vertebrates in the world. In spite of this, and the widespread release of nitrogenous compounds into the environment, research on the impact of this pollution on Neotropical species remains limited. The aim of this study was to assess the sensitivity of one anuran species inhabiting in the Brazilian Atlantic Forest (Dendropsophus haddadi) to NaNO₃ by an acute exposure laboratory experiment, addressing also whether carryover effects exist. Larval mortality increased as time went on in the case of the highly polluted treatments, which also affected swimming performance. Mean lethal concentration (LC₅₀) values revealed that the sensitivity of the study species to NaNO₃ was similar to that described for other amphibians, both tropical and temperate species. Additionally, larvae exposed to moderate levels of pollution significantly increased final mass. In spite of this, once larvae were transfered into clean water, no further mortality was recorded, and swimming performance improved. These results indicate that tropical species may not be more vulnerable to chemical pollution than temperate ones, and suggest that they are able to recover from acute short exposure to nitrogenous compounds, all of which represent a new addition to the knowledge of the vulnerability of Dendropsophus haddadi to pollution and, thus, to Neotropical ecotoxicology.